Acute Exacerbation of Previously Unrecognized Interstitial Lung Disease in a Functionally Independent Nonagenarian: A Case Report.

Acute exacerbation of interstitial lung disease (AE-ILD) is associated with high mortality and a poor prognosis. Particularly in the oldest-old population, comprehensive assessment, including factors contributing to delays in seeking medical care and decisions regarding treatment eligibility, is clinically important. A 92-year-old man, who had been independent in activities of daily living (ADLs), ambulated with a cane, and lived at home before admission, was treated for presumed pneumonia at a local clinic because of a cough. However, his symptoms did not improve, and he was referred to our hospital because of worsening dyspnea. Chest computed tomography (CT) revealed bilateral ground-glass opacities and pre-existing pulmonary fibrosis. He was clinically diagnosed with previously undiagnosed interstitial lung disease (ILD) complicated by bacterial pneumonia, and treatment with antibiotics and corticosteroids was initiated. His respiratory status initially improved; however, chest CT performed on hospital day 5 showed worsening bilateral ground-glass opacities. On hospital day 6, his respiratory status rapidly deteriorated, leading to a diagnosis of AE-ILD. Despite treatment with corticosteroid pulse therapy and cyclophosphamide, he ultimately died. In this case, the delay in seeking medical care may have been related not only to the patient's awareness of his disease but also to healthcare system factors, including the timing of referral to our hospital and the availability of continuous follow-up. Although the patient was 92 years old, his pre-admission ADLs were preserved; therefore, aggressive treatment was selected based on his functional status rather than chronological age alone. Nevertheless, this case suggests that AE-ILD can follow a rapidly progressive and fatal course even in patients with preserved ADLs. In the management of AE-ILD in the oldest-old population, the factors underlying delays in seeking medical care should be assessed from both patient- and healthcare system-related perspectives. Furthermore, treatment eligibility should not be determined solely on the basis of chronological age; individualized care based on a comprehensive assessment of ADLs and the patient's overall clinical background is essential.